1. Field of the Invention
The present invention relates to a method of manufacturing a blade which is one component of a runner, an impeller, etc. for fluid machinery, such as a pump, a water-turbine or a pump-turbine.
2. Description of the Related Art
FIG. 6 illustrates a conventional method of manufacturing a blade for fluid machinery by working, such as plastic working, a plate-shaped component. As step 1, a plate-shaped component 1 is deformed (worked) to obtain an intermediate formed material 2 (preform) which has a predetermined shape, keeping a constant thickness. Then, as step 2, at least one side of the preform 2 is machined, such as by computer numerical control (CNC) machining, into a final blade form (blade 3) having the desired blade cross-section(s).
The above-described method is generally efficient for simple blade shapes. However, in the case of a blade having a complex three-dimensional-curved surface, the machining step is much more involved, thus reducing manufacturing efficiency.
Moreover, due to the complex curved surfaces of the preform, it is often difficult to firmly clamp the preform in a fixture so that accurate machining can be performed.